Delphiniums are a stunning addition to any garden, known for their tall spikes of vibrant flowers that can reach up to six feet in height. While these perennials thrive in many regions, growing delphinium in Colorado presents unique challenges and rewards due to the state’s diverse climate and soil conditions. In this article, we will explore how to successfully cultivate delphinium in Colorado, from selecting the right varieties to proper care and maintenance.
Before delving into the specifics of growing delphinium, it’s essential to understand what these plants are and what they require. Delphiniums belong to the Ranunculaceae family and encompass numerous species, with Delphinium elatum and Delphinium grandiflorum being among the most popular for gardeners. These flowers typically bloom in shades of blue, purple, pink, and white, making them a favorite for perennial gardens.
When selecting a delphinium variety for your Colorado garden, it’s crucial to choose those that are well-suited to the local climate. Some recommended varieties include:
Pacific Giants: Known for their towering spikes and large blooms, Pacific Giants are ideal for Colorado’s cooler climates and can withstand some harsh weather.
Magic Fountains: This variety is shorter (about 2-3 feet) and boasts a mix of colors. They are more tolerant of heat and drought, making them suitable for lower elevations.
Cottage Delphiniums: More compact than other types, cottage delphiniums are perfect for smaller spaces and can also handle Colorado’s varying temperatures.
In Colorado, timing is crucial for successful delphinium growth. The best time to plant delphiniums is in early spring after the last frost or in fall before the winter chill sets in. Starting seeds indoors 8-10 weeks before the last frost date is a great option if you want a jump start on the growing season.
The foundation of a healthy delphinium plant lies in its soil. Here’s how to prepare your garden bed:
Delphiniums thrive in well-draining soil that is rich in organic matter. The ideal pH level for delphiniums ranges between 6.0 and 7.0. Here’s how to prepare your soil:
Delphiniums require full sun—ideally at least six hours per day—so choose a location that receives ample sunlight. When planting, space your delphiniums about 18-24 inches apart to allow for air circulation and reduce the risk of disease.
Once your garden bed is prepared, it’s time to plant your delphinium:
Proper care is vital for robust growth and blooming:
Delphiniums prefer consistent moisture but do not fare well with overly wet conditions. Water deeply once or twice a week during dry spells but allow the top inch of soil to dry out between waterings.
Fertilize your delphiniums with a balanced fertilizer early in the growing season, ideally when new growth appears. An all-purpose garden fertilizer or one specifically formulated for flowering plants will suffice.
Applying a layer of organic mulch around your plants can help retain moisture, suppress weeds, and regulate soil temperature—important factors in Colorado’s variable climate.
Due to their height, some delphinium varieties may require support as they grow. Using stakes or cages will help prevent them from falling over during storms or strong winds common in Colorado.
Like any plant, delphiniums can be susceptible to pests and diseases. Here are some common issues gardeners may encounter:
Aphids: These small insects suck sap from plants. Regularly inspecting your plants can help catch infestations early; use insecticidal soap if needed.
Slugs and Snails: These creatures thrive in moist environments. To deter them, remove debris around plants and use beer traps or iron phosphate bait as needed.
Powdery Mildew: This fungal disease appears as white powdery spots on leaves. Ensuring good air circulation through proper spacing helps prevent this issue.
Botrytis Blight: This fungal infection can affect flowering parts by causing moldy spots. Remove affected flowers immediately to minimize spread.
Delphiniums are perennial but may not survive harsh winters without proper care:
Cutting Back: Once flowering ends in late summer or early fall, cut back spent flower stalks to about 6 inches above ground level.
Mulching: Apply a thicker layer of mulch around the base of each plant before winter sets in to protect roots from freezing temperatures.
Watering Before Freeze: Ensure your plants receive adequate moisture before the ground freezes; this helps them survive through winter dormancy.
Growing delphinum in Colorado can be an incredibly rewarding experience when approached with knowledge and care. By choosing suitable varieties, preparing your planting bed adequately, providing consistent water and nutrients, managing pests effectively, and preparing for winter conditions, you can cultivate a thriving garden filled with these magnificent blooms year after year. With patience and dedication, you’ll enjoy stunning displays that will elevate your garden’s beauty while attracting pollinators such as bees and butterflies throughout the growing season. Happy gardening!